Rotating Shoulders

Hey All,

I am new here and this is my first thread, I have been playing golf for about 5 months and it's only the last month I have got serious about it.

When driving I always tend to push the shot and then it tunrs into a slice, a rather severe one too. Recently I have found that if I start to rotate my shoulders and probably hips right around as I make contact with the ball I end up hitting it straighter than usual, so by the end of my swing I have fully rotated and my chest is just about pointing in the direction where I hit the ball.

However the problem is I cannot consistantly do this, I am a rather hugely built guy and it feels so unatural, so my question what can I do to help me rotate properly to hit through the ball which prevents me from slicing?

Is there a routine/drill I could do? Is there a free lesson online which helps me to do this properly and consistantly?